Model comparison
Gemini 2.5 Flash vs o3-pro
o3-pro is the stronger model overall, scoring 42.9 to 39.3 on the Noometry Index. Gemini 2.5 Flash costs 41× less per token, which makes it the better buy when o3-pro's lead doesn't matter for your workload.
Last verified . 12 shared benchmarks.
GoogleSummary
- They share 12 benchmarks with published results for both. Gemini 2.5 Flash scores higher in 1 category and o3-pro in 4 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in long context, where o3-pro leads 72.2 to 47.5.
- The biggest single-benchmark swing is Aider Polyglot: 55.1% for Gemini 2.5 Flash and 84.9% for o3-pro.
- Gemini 2.5 Flash is cheaper at $0.30 / $2.50 per million input/output tokens, against $20 / $80 for o3-pro.
- Gemini 2.5 Flash accepts more context: 1.05M tokens versus 200K.
Side by side
| Gemini 2.5 Flash | o3-pro | |
|---|---|---|
| Provider | OpenAI | |
| Noometry Index | 39.3 | 42.9 |
| Released | 2025-04-17 | 2025-06-10 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 200K |
| Max output | 66K | 100K |
| Input $ / M tokens | $0.30 | $20 |
| Output $ / M tokens | $2.50 | $80 |
| Results tracked | 54 | 12 |
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Category by category
Coding o3-pro leads
Gemini 2.5 Flash: 35.8 (#220), o3-pro: 55.5 (#24)
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| Aider Polyglot | 55.1% | 84.9% |
| WeirdML | 41.9% | 58.2% |
| SWE-bench Verified (bash only) | 28.7% | — |
| LMArena Coding | 1424 | — |
| ALE-Bench | 661.88 | — |
Agentic & Tool Use Not comparable
Gemini 2.5 Flash: 30.8 (#74), o3-pro: —
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| Terminal-Bench | 17.1% | — |
| Berkeley Function Calling Leaderboard | 56.2% | — |
| TheAgentCompany | 41.1% | — |
| BALROG | 33.5% | — |
| Vending-Bench 2 | 548.84 | — |
Reasoning o3-pro leads
Gemini 2.5 Flash: 18.1 (#286), o3-pro: 23.8 (#171)
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| ARC-AGI-2 | 2.5% | 4.9% |
| Kagi LLM Benchmark | 56.8% | 72.1% |
| ARC-AGI-1 | 33.3% | 59.3% |
| DTBench | 76.5% | 86.9% |
| LMCA | 27.5% | 38.5% |
| Epoch Capabilities Index | 143.03 | 147.42 |
| SimpleBench | 41.2% | — |
| CritPt | 1.1% | — |
| EnigmaEval | 2.7% | — |
| LMArena Hard Prompts | 1422 | — |
| ForecastBench | 60.6 | — |
Math Not comparable
Gemini 2.5 Flash: 39.9 (#98), o3-pro: —
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 73.1% | — |
| Omni-MATH | 38.5% | — |
| LMArena Math | 1415 | — |
| FrontierMath (Feb 2025 set) | 4.8% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |
Knowledge Gemini 2.5 Flash leads
Gemini 2.5 Flash: 36.4 (#168), o3-pro: 29.5 (#238)
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| Confabulations | 16.8% | 14.2% |
| Vectara Hallucination Rate | 7.8% | 23.3% |
| Humanity's Last Exam | 12.1% | — |
| MMLU-Pro | 63.9% | — |
| GPQA (HELM) | 39% | — |
| LMArena Expert | 1426 | — |
Multimodal Not comparable
Gemini 2.5 Flash: 41.8 (#32), o3-pro: —
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| LMArena Vision | 1253 | — |
| GeoBench | 76% | — |
| VPCT | 46.2% | — |
| SpatialViz-Bench | 36.9% | — |
Multilingual Not comparable
Gemini 2.5 Flash: 52.3 (#88), o3-pro: —
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| LMArena Non-English | 1409 | — |
| LMArena Chinese | 1450 | — |
| LMArena French | 1433 | — |
| LMArena German | 1418 | — |
| LMArena Japanese | 1405 | — |
| LMArena Korean | 1385 | — |
| LMArena Russian | 1415 | — |
| LMArena Spanish | 1421 | — |
Instruction Following Not comparable
Gemini 2.5 Flash: 75.7 (#54), o3-pro: —
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| IFEval | 89.8% | — |
| LMArena Instruction Following | 1405 | — |
Long Context o3-pro leads
Gemini 2.5 Flash: 47.5 (#17), o3-pro: 72.2 (#1)
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| Fiction.LiveBench | 77.8% | 97.2% |
| LMArena Longer Query | 1419 | — |
Writing & Preference o3-pro leads
Gemini 2.5 Flash: 53.8 (#157), o3-pro: 57.1 (#133)
| Benchmark | Gemini 2.5 Flash | o3-pro |
|---|---|---|
| Short-Story Creative Writing | 76.5% | 84.4% |
| LMArena Text | 1417 | — |
| LMArena Creative Writing | 1400 | — |
| EQ-Bench Creative Writing | 1137 | — |
| WildBench | 81.7% | — |
| LMArena Multi-Turn | 1408 | — |
Frequently asked questions
Is Gemini 2.5 Flash better than o3-pro?
o3-pro is the stronger model overall, scoring 42.9 to 39.3 on the Noometry Index. Gemini 2.5 Flash costs 41× less per token, which makes it the better buy when o3-pro's lead doesn't matter for your workload.
Which is cheaper, Gemini 2.5 Flash or o3-pro?
Gemini 2.5 Flash is cheaper. It lists at $0.30 per million input tokens and $2.50 per million output tokens; o3-pro lists at $20 and $80.
Is Gemini 2.5 Flash or o3-pro better for coding?
o3-pro scores higher on coding benchmarks: 55.5 versus 35.8 in the Noometry coding category.
Which has the bigger context window?
Gemini 2.5 Flash does, with 1.05M tokens against 200K.
How many benchmarks do Gemini 2.5 Flash and o3-pro share?
12 benchmarks have published results for both models. Gemini 2.5 Flash has 54 scored results on Noometry and o3-pro has 12.